This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-126242, filed Apr. 24, 2001, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an ultrasound diagnostic apparatus equipped with an internal probe that can be inserted into a body cavity such as a blood vessel or bile duct.
2. Description of the Related Art
Recently, operation of directly inserting an internal probe, for example a small diameter probe inserted into a human body cavity, e.g., a blood vessel or bile duct of a patient, diagnosing a lesion, stricture, and the degree of invasion of a cancer in a tube wall, and determining a surgical operation plan and postoperative therapeutic effect has been done, together with various medical treatments such as TAE (Transcatheter Arterial Embolization), PTCA (Percutaneous Transluminal Coronary Angioplasty), and PTCR (Percutaneous Transluminal Coronary Recanalization). An operator must therefore comprehend the entrance position of a catheter or internal probe and check whether the distal end portion has reached a region to be diagnosed or treated.
Conventionally, a region which a catheter or internal probe enters is imaged by using an X-ray fluoroscopic apparatus, and the operator monitors the position of the distal end of the catheter or internal probe while watching the X-ray image displayed on a monitor. In monitoring by X-ray fluoroscopy, however, the operator is inevitably exposed to X-rays as well as the patient.
For this reason, a method of checking the position of the distal end of a catheter or internal probe by using an ultrasound diagnostic apparatus instead of an X-ray fluoroscopic apparatus has been proposed. The ultrasound diagnostic apparatus is designed to apply ultrasound beams from the body surface to the inside of the body using an external probe, receive an echo signal reflected by a region where acoustic impedance varies, and reconstruct an image. A catheter or internal probe has a smooth surface and is bent inside the body in general. For this reason, ultrasound beams incident from the body surface are regularly reflected by the surface of the catheter or internal probe, and do not return to the body surface probe in many instances. This makes it very difficult to detect a position and form an image. Under the circumstances, a method is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 4-129543, in which a transducer is mounted on the distal end of a catheter or internal probe, and position information is obtained by receiving the ultrasound beam transmitted from an external probe.
A conventional ultrasound diagnostic apparatus is generally designed as a system to reconstruct and display a cross section image by performing scanning within a plane by transmitting ultrasound beams from a one-dimensional array ultrasound transducer. For this reason, attempts have been actively made to obtain 3-D information by acquiring diagnostic images while moving a probe as an ultrasound beam transmitting/receiving unit, and new diagnostic possibility is expected from display of a 3-D image in an ultrasound diagnostic apparatus. In practice, researches have been made by, for example, manually or mechanically moving an abdominal convex probe or linear array probe and using a transesophageal multi-plane probe having a mechanism of rotating an electronic sector probe. However, it takes a considerably long period of time to obtain 3-D information by using the above technique, as compared with the conventional cross section image scanning technique. Hence, movement information cannot be obtained from a target that moves quickly, such as the heart. In addition, if a probe cannot be satisfactorily fixed, even an image of an abdominal portion, which does not move so quickly as the heart, greatly deforms.
Under the circumstances, a 3-D ultrasound diagnostic apparatus is under study, which includes an ultrasound probe having 2-D phased array ultrasound transducers and a function of stereoscopically scanning an ultrasound beam, and can scan and display a 3-D volume image with a corresponding frame.
Conventionally, importance is attached to the resolution of images in an intravascular ultrasound (IVUS) apparatus/intraductal ultrasound (IDUS) apparatus/endoscopic ultrasonography (EUS) apparatus having an internal probe. However, the walls of a blood vessel and body cavity cannot be observed sufficiently deep because of lack of penetration.
It is an object of the present invention to solve the problem associated with the lack of penetration of an ultrasound diagnostic apparatus using an internal probe.
An ultrasound diagnostic apparatus according to the present invention includes first and second probes. The inside of an object to be examined is scanned with a first ultrasound beam through the first probe to acquire first ultrasound image data associated with the object. The inside of the object is scanned with a second ultrasound beam through the second probe to acquire second ultrasound image data associated with the object. The second ultrasound image data is synthesized with the first ultrasound image data on the basis of the position of the first probe relative to the second probe, which is detected by a position detector.
Additional objects and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.